A Sulfur Amino Acid–Free Meal Increases Plasma Lipids in Humans

Abstract

The content of sulfur amino acid (SAA) in a meal affects postprandial plasma cysteine concentrations and the redox potential of cysteine/cystine. Because such changes can affect enzyme, transporter, and receptor activities, meal content of SAA could have unrecognized effects on metabolism during the postprandial period. This pilot study used proton NMR ((1)H-NMR) spectroscopy of human plasma to test the hypothesis that dietary SAA content changes macronutrient metabolism. Healthy participants (18-36 y, 5 males and 3 females) were equilibrated for 3 d to adequate SAA, fed chemically defined meals without SAA for 5 d (depletion), and then fed isoenergetic, isonitrogenous meals containing 56 mg·kg(-1)·d(-1) SAA for 4.5 d (repletion). On the first and last day of consuming the chemically defined meals, a morning meal containing 60% of the daily food intake was given and plasma samples were collected over an 8-h postprandial time course for characterization of metabolic changes by (1)H-NMR spectroscopy. SAA-free food increased peak intensity in the plasma (1)H-NMR spectra in the postprandial period. Orthogonal signal correction/partial least squares-discriminant analysis showed changes in signals associated with lipids, some amino acids, and lactate, with notable increases in plasma lipid signals (TG, unsaturated lipid, cholesterol). Conventional lipid analyses confirmed higher plasma TG and showed an increase in plasma concentration of the lipoprotein lipase inhibitor, apoC-III. The results show that plasma (1)H-NMR spectra can provide useful macronutrient profiling following a meal challenge protocol and that a single meal with imbalanced SAA content alters postprandial lipid metabolism.

Multifractal Analysis for Nutritional Assessment

“…Significant changes in plasma lipid parameters (cholesterol, CHOL; triglycerides, TG; high-sensitivity C-reactive protein, hsCRP; apolipoprotein C3, apoC3) occurred in association with SAA intake [18], so we tested whether the multifractal descriptors of the plasma 1 H NMR spectra also associated with these clinical measurements. Higher values of CHOL, TG, hsCRP, and apoC3 are indicators of increased cardiovascular disease risk including, so we performed a regression analysis with a model of each of the four measurements as response, H , LS, and Std as quantitative variables and subject as a qualitative variable.…”

“…This study was performed by reanalysis of 1 H NMR spectral data from previously published studies [17], [18] that were reviewed and approved by the Emory University Investigational Review Board. The blood samples were collected with EDTA, and spectral data were generated for the different projects using procedures and settings with the intent to allow spectral data from different studies to be used for comparative analyses in a cumulative spectral database.…”

“…For the primary comparison of effects of SAA intake, 8 participants in a controlled cross-over study received an isoenergetic, isonitrogenous diet sequentially without and with SAA [18]. Data for 12 critically ill ICU patients were from baseline samples collected upon admission into a double-blind study of albumin treatment [23].…”

“…Healthy participants (18–36 y, 5 males and 3 females) were equilibrated for 3 d to adequate SAA, fed chemically defined meals without SAA for 5 d (depletion) and then fed isoenergetic, isonitrogenous meals containing 56 mg⋅kg −1 ⋅d −1 SAA for 4.5 d (repletion) [17]–[19]. Results showed effects of SAA intake on lipids, some amino acids, and lactate [18].…”

Nutritional Metabolomics: Progress in Addressing Complexity in Diet and Health

“…No individual had the average response pattern, i.e., even though an average response was described, this average was not a good descriptor of an individual. A crossover study of sulfur amino acid insufficiency similarly showed that while about half of the individuals showed a common response pattern, no individual had an average response pattern (72). Thus, nutritional metabolomic data underscore the need to transition to complex biosystems approaches to transform nutrition to a personalized level.…”